Percussion or impact device



Dec. 14, 1965 B. SCHWEIZER 3,223,210

PERCUSSION OR IMPACT DEVICE Filed June 20, 1960 4 Sheets-Sheet 1 INVENTOR:

BEN N 0 SCHWEIZER Dec. 14, 1965 SCHWEIZER v 3,223,210

PERCUSSION OR IMPACT DEVICE Filed June 20, 1960 m 4 Sheets-Sheet 2 r. l 9 8 :10 11;- 4 181238 .13 i4 lil 6 as M .IWENTOR BENNO SCHWE/Z ER Dec. 14, 1965 SCHWEIZER 3,223,210

PERCUSSION 0R IMPACT DEVICE Filed June 20, 1960 4 Sheets-Sheet 5 FIG. IO FIG.

INVENTOR. 554/4/0 so/n/e/ze BY ML TM Dec. 14, 1965 B. SCHWEIZER 3,223,210

PERCUSSION OR IMPACT DEVICE Filed June 20, 1960 4 Sheets$heet 4 INVENTOR BENNO SCHWL'IZER BY M W ATTORNEYS United States Patent C 3,223,210 PERCUSSION GR IMPACT DEVICE Benno Schweizer, Stuttgart, Germany, assignor to Firrna C. & E. Fein, Stuttgart, Germany Filed June 20, 1960, Ser. No. 37,454 Claims priority, application Germany, June 20, 1959,

7 Claims. or. 192 .02

Percussion or impact-operated screw tightening devices or similar mechanical apparatus are used for tightening nuts, bolts and the like, in such manner that the force or power of a motor, which is driven by any suitable means, is transferred by way of an impact or percussion coupling to the structural part which has to be tightened, using rotational impacts.

However, it is often desired to tighten screws of various sizes by screw tightening means of a unitary or single size, or to tighten screw connections to only a certain predetermined degree of tightness.

Impact or percussion-operated screw tightening devices having torque-controlled means for discontinuing the drive are used for this purpose. In one of the prior art devices the rebound of the percussion or impact body, after having struck the nut or the bolt, is used to discontinue operation of the device. However, the rebound does not sulfice, in cases of low operating torque, to operate a switch or the like. Therefore, it is necessary to use additional elements, one of which may be an energy storing spring, in order to obtain, even in case of low torque, a sufficiently large force or power and a resulting stroke for operating the switch. Most of the rebound is transmitted by means of a linkage to the switch of the device.

It is also known to use the impact of the impact body for discontinuing operation of the device. However, prior constructions of this type have a specially insertable tool whereby the overall construction becomes comparatively complicated and expensive. Furthermore, the length of the device is somewhat extended.

It is an object of the present invention to provide means resulting in the elimination of the disadvantages of the prior art percussion devices for tightening screws, or the like, having torque-controlled means for discontinuing the drive.

It is another object of the present invention to provide means facilitating an especially simple construction whereby the switching operation is etfectuated by an impact or percussion body operating a switch, which body makes an axial movement, the impact body having a part which is constructed as an axially movable mass.

It is another object to provide means for ensuring that even in case of a low operating torque the impact is sufficiently large for operating a switch. Consequently, the need for a specially insertable tool is eliminated, since a part, which is already present in the percussion screw tightening device, has a complementary formation whereby the proportions of the masses in the device similarly remain substantially unchanged. Additionally, the overall size of the device is not changed pursuant to the invention.

It is a feature of the invention to provide an impact body which is formed as a coupling, whereby one part of the coupling is arranged for aXial movement. This coupling may be positioned in the direct line of power of the tool or it may be positioned in a direction parallel to said line of power. Preferably, the percussion or impact body is in the form of a jaw coupling wherein at least some portions of cooperating lugs are disposed obliquely relative to one another. Due to the inclined Patented Dec. 14, 1965 surfaces of the lugs, there results an axial movement of at least one part of the coupling.

Furthermore, a certain amount of damping of the impact is obtained in the case of the disposition of the coupling in the direct line of power. This damping action is frequently desired in order to prevent the bolt or the nut from being destroyed. It also is possible by means of the damping of the impact to slowly approach the preset final amount of force at which the tool is automatically switched off.

Pursuant to another feature of the invention, provi sion is made for an abutment for limiting the movement of the parts relative to each other.

Preferably, every part of the coupling, which is disposed in the direct line of power, has lug groups, each of which comprises one tooth, which is oblique or slanted on one side and has a perpendicular face or surface on the other side thereof, and a second tooth having perpendicular faces or surfaces on both sides thereof, whereby the second tooth is disposed at a small distance from the slanted side of the first tooth, and whereby the slanted sides of the teeth of both coupling parts are arranged at the same angle to the base surface or face.

It is preferable to arrange the distances between the lug groups so as to correspond to the arcuate length of the lug groups themselves. In a coupling constructed in this manner, the slanted or oblique sides of the teeth glide along one another during the impact action of the tool whereby to provide concomitantly the aforementioned damping of the impact and an axial movement of one part of the coupling. No damping occurs in the opposite direction of rotation, corresponding to the loosening of screws, because the perpendicularly disposed sides of the teeth are then abutting against one another.

Furthermore, such a construction of the groups of lugs permits presetting the parts of the coupling in such way that a lug group of one part always fits into the space between two lug groups of the other part. Since the lug groups end on both sides in perpendicularly arranged faces, a perfectly stationary connection can be achieved, and it is possible to eliminate thereby the damping effect and the switching operation.

It is beneficial to provide for an area which runs parallel to the base face on both lugs of each lug group. It is advantageous to arrange three lug groups on each part of the coupling because a special guide means is no longer necessary for the parts of the coupling relative to one another.

In a coupling which is disposed parallel to the line of power, it is preferable to provide for compression springs acting between the two parts of the coupling in the circumferential direction thereof for returning the parts to the original position thereof. A particularly simple form of lug is obtained by using bolts having a slanted or oblique collar on the upper part thereof, which bolts are inserted only in bores of the pertinent parts of the coupling.

These and other objects of the invention will become further apparent from the following detailed description, reference being made to the accompanying drawings showing preferred embodiments of the invention.

In the drawings, which illustrate the best modes presently contemplated for carrying out the invention:

FIG. 1 illustrates an impact or percussion-operated screw tightening device, partly in section;

FIG. 2 is a side view, on an enlarged scale, of the impact body, formed as a coupling;

FIG. 3 illustrates the developed circumference of parts shown in FIG. 2;

FIG. 4 illustrates the developed circumference of the parts, as shown in FIG. 3, having the lug groups positioned relative to one another in such way that they form a stationary connection;

FIG. is a view similar to FIG. 3 showing the parts of the coupling displaced against one another;

FIG. 6 is a longitudinal section of the head portion of an impact or percussion-operated screw tightening device, partly broken away, illustrating another embodiment of an impact or percussion body, and taken along the line VI-VI in FIG. 7;

FIG. 7 is an end view of the impact body shown in FIG. 6, taken from the line VIIVII in FIG. 6;

FIG. 8 is a partial longitudinal section of the impact or percussion body shown in FIGS. 6 and 7, taken along the line VIIIVIII of FIG. 7;

FIG. 9 is an enlarged transverse sectional view of the switching mechanism in an inoperative or rest position;

FIG. is a view similar to FIG. 9 with the parts in a switching-in position;

FIG. 11 is a view similar to FIG. 9 with the parts in a switching-off position; and

FIG. 12 is an exploded perspective view of the embodiment of the invention shown in FIGS. 6, 7 and 8.

Referring now to the drawings in detail, there is shown a percussion or impact-operated screw tightening device 50 pursuant to the present invention. Device 50 comprises a handle 1 having a built-in switch 2, a motor housing 3 and a gear housing 4. In the gear housing 4 there is mounted a cylindrical body 5 having a plurality of concentric steps or planetary gears rotatably arranged, which are coupled with the shaft 6 of the motor 51. The cylindrical body 5 has, in addition, a shaft 7 which extends into a bore 8 defined in a tool spindle 9. The tool spindle 9 can be connected with a wrench or the like in a conventional manner not shown in the drawing. The tool spindle 9 has, on the portion thereof which is disposed within the gear housing 4, two lugs 10 which engage the lugs 11 of a percussion or impact body 12, within the gear housmg.

The percussion or impact body or means 12 is coupled to the cylindrical body 5 by rods 13 having ball shaped ends 52. The rods are journalled in universal joints on both ends thereof. A compression spring 14 is disposed between the percussion or impact body 12 and the cylindrical body 5, the spring abutting against both of said bodies.

The device 50 is shown in FIG. 1 and FIG. 6 in its initial or starting position, that is, the impact body 12 is at the maximum possible distance away from the cylindrical body 5 and its lugs 11 are in mesh with the lugs 10 of the tool spindle 9.

When the shaft 6 of motor 51 is rotated, and when the lugs 10 and 11 engage each other, the impact body 12 is rotated with respect to the cylindrical body 5 and drive shaft 6, respectively, as soon as a certain torque, which is controlled by the force of the compression spring 14, is exceeded. Thereupon the impact body 12 is displaced, against the force or bias of the spring 14, in the axial direction because of the inclined position of the rods 13 provided with the ball ends 52, in the direction toward the cylindrical body 5 until the lugs 10 and 11 are disengaged. When the lugs 10 and 11 have passed or become completely disengaged from each other, the compression spring 14 moves the impact body 12 rapidly back into its original position. The lugs 11 strike the lugs 10 with the total stored kinetic energy of the impact body 12 and thus drive, by means of the tool spindle 9, the screw or bolt (not shown in the drawing) in a forward direction through a predetermined angle.

The impact body 12 is shown in FIG. 2 in the form of a jaw coupling having two complementary coupling parts 15 and 16. The ball ends 52 are rotatably held in place in part 16 and part 15 has lugs 11 which are arranged for engaging the lugs 10.

, Each coupling part 15 and .16 ha a shown in FIG- 3, three lug groups 17. Each lug group includes a tooth 20 having, relative to base surface 24, an inclined or oblique face or surface 18 on one side thereof and a perpendicular face or surface 19 on the other side thereof. A second tooth 21 is disposed a predetermined distance from the adjacent, inclined face or surface 18, and tooth 21 has perpendicular faces 22 and 23 on both sides thereof. Furthermore, both teeth have portions 25 and 26 parallel to the base face or surface 24.

The distance between two lug groups 17 corresponds to the length 28 of the arc defined by the individual lug group 17. The inclined faces or surfaces 18 of the teeth 20 have the same angle relative to the base face or surface 24 in both of the coupling parts 15 and 16. The starting or initial position is shown in FIG. 2 and FIG. 3.

When the coupling part 15 is loaded by the engagement of its lugs 11 with the lugs 10 of the spindle and when the coupling part 16 starts to rotate, the coupling part 15, as shown in FIG. 5, is displaced on account of the inclined faces 18 of the teeth 20 in an axial direction toward the tool spindle 9. The degree of this displacement or separation depends upon the working or operating torque. When the axial displacement becomes large enough, a pin 35 which protrudes into the path of movement of the coupling part 15, is moved with the latter. Pin 35 is coupled by means of a rod 29 with the pivoted trigger 53 of the switch 2 for motor 51 and operates the switch to its initial or starting position to de-energize the motor.

The desired working or operating torque is adjusted by varying the distance between the coupling part 15 and the pin 35 by turning the nut 30 in a corresponding direction, said nut interconnecting the two portions 29a and 29b of rod 29, so as to make the latter longer or shorter.

In order to obtain positive contact or engagement between the coupling parts 15 and 16, a resilient element, for example, the compression spring 31, is provided. Said spring is preloaded so as to also influence the axial displacement of the coupling part 15.

The compression spring 31 is seated on a sleeve bushing 32. One end of spring 31 abuts against a collar 33 of the sleeve bushing and the other end thereof abuts against the coupling part 15. The shoulder 34 of the sleeve bushing 32 is urged against the coupling part 16 by the compression spring 14. The movement of the coupling parts 15 and 16 relative to one another is limited by the front face or surface 36 of the sleeve bushing 32, so that said sleeve bushing also functions as a limiting abutment or detent for the axial movement of the coupling part 15.

Since the length 28 of the lug group 17 and the distance 27 between adjacent lug groups 17 is equal, it is possible to rotatably shift the coupling parts 15 and 16 ,by so that, correspondingly, a lug group 17 of one coupling part gets into the distance 27 of the other coupling part, as shown in FIG. 4. Consequently, a stationary coupling between the coupling parts 15 and 16 can be obtained, and thus switching of the device 50, depending upon the torque, is prevented.

As mentioned above, the coupling parts 15 and 16 are capable of being locked for continuous operation and without shut-off upon reaching a predetermined torque value by positioning the coupling parts as indicated in FIG. 4. Thus it can be readily seen that the purpose of the part 21 with the vertical edges on each side is to provide a locked clutch engagement of the parts 15 and 16 as indicated in FIG. 4. However, as pointed out previously, when the element 20 with the inclined face 18 is positioned to cooperate with a similarly inclined face of the coupling part 15, then the device operates to shut off the motor when the torque which is applied from the driving shaft 6 to the tool spindle 9 exceeds a predetermined amount.

When the operator pulls the trigger element 53, it causes movement of a switch actuating arm 60 to displace a movable element 62 of the switch 2 and start the motor 51. The motor 51 continues to operate until a torque sufiicient to effect the riding up of the inclined surface 18 of the element 16 of the similarly inclined surface on the element 15 causes axial displacement of the latter. This axial displacement continues until a portion on the movable element 15 contacts the pin 35 and displaces it therewith. This displacement causes a cam member 64 on the end of the rod 29a to displace a switch camming member 66 and the member 60 on the switch element 62 to shut otf the motor 51. Thus, despite the fact that the operator still holds the trigger 53 in an operating position, the driving motor is automatically shut off due to the reaching of the predetermined torque.

As indicated in FIG. 9, the trigger 53 is shown in an inoperative or rest position and in such position power which is supplied from connecting cables 70 to the switch 2 is not delivered through the connecting cable 72 to the motor 51 and hence the motor 51 is not operated.

In FIG. the trigger 53 is pressed inwardly to displace the movable elements 62 and to load spring 74 and a return spring 76. The spring 76 is tensioned by the pivotal movement of the switching-elf lever 78 which is rocked counterclockwise from the position indicated in FIG. 9 to the position indicated in FIG. 10. The switching otf lever 78 is arranged for movement with the trigger 53 by means of a pin 84.

An actuating arm or intermediate lever 60 presses against the movable elements 62 to actuate the switch 2. As indicated in FIG. 10, the parts are in position to connect through the cables 72 to the motor 51 to operate the motor.

In the pivoting of the switching-off lever 78 a spring 76 anchored at a holding plate 86 and to the pivoting lever 73 is tensioned.

In the position indicated in FIG. 11, the device is switched off and this occurs when the rod 29a is moved toward the left in the direction of the arrow as indicated in FIG. 10 to cause the cam member 64 to rock the sWitching-oif lever 78 counterclockwise. The switchingoff lever 78 pivots about a bearing point 84. One arm of the switching-off lever 78 therefore rocks downwardly to lower the support of the actuating arm 60 to permit the switch spring 74 to move the movable element 62 to the left and the actuating arm 60 to a substantially vertical position. To accomplish this the switching spring 74 must be stronger than the spring A which exerts a counterrocking movement on the switching-01f lever member 78. By this movement the spring A is tensioned.

The machine is now at rest and the operator releases the trigger 53 to cause the spring A to again move the intermediate lever or actuating arm 60 and the switchingoff lever 78 into a starting position as indicated in FIG. 9.

The movement of the trigger 53 is limited by the extended bearing pin 80 which engages in the circular recess 82 defined in a lower holding plate 86. (The lower holding plate 86 has only been indicated in the right hand edge portion for clarity of illustration.)

Thus by the sequence of operation indicated in FIGS. 9-11, the switching-off of the machine is accomplished without the operator taking any action whatsoever.

Another embodiment of the invention is shown in FIGS. 6, 7, 8 and 12, having another form of percussion or impact body or means 12A. Impact means 12A comprises stationary part 38 which transmits the power directly from the rods 13 provided with ball-shaped ends without intermediate links to the lugs 18 of the tool spindle 9. An inertia mass body 39 is rotatably and axially movably journalled in the interior of the part 38. Each one of the parts 38 and 39 has respective bolts 40 which are inserted in complementary bores 41.

Each bolt 40 has a collar 42 on its upper end and each collar has an inclined or slanted face or surface 54. When a movement of the two parts 38 and 39, relatively to one another, occurs, the slanted or inclined faces of the bolts 40 glide or slide on one another, whereby part 38 is displaced in the direction of the arrow 43 in FIG. 8.

When the ring 44, which is carried in lugs 10 of part 39 and which abuts against shoulders on these lugs, as best seen in FIG. 8, strikes pin 35, the switch 2 is operated in the same manner as previously described, and the device is switched otf or rendered inoperative. It will be noted from FIG. 7, that ring 44 surrounds, with some clearance, the lugs 11 of part 38. In order to return part 39 into its initial or starting position, compression springs 45, acting in a peripheral direction, are provided, which abut against both parts 38 and 39.

The rotary movement of part 39 is limited by abutments or detents 46 provided on part 38. While in the first embodiment the jaw coupling is inserted into the line of power of the tool, the coupling in the second embodimerit is arranged parallel to the line of power, so that no forces are transmitted by part 39.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. A rotary impact hand tool comprising a rotatable shaft, an electric motor connected to said shaft to rotate said shaft, a tool spindle driven by said shaft, torque clutch means connected to said shaft and connectable to said tool spindle, including first and second rotatable elements having mating coupling surfaces disposed obliquely, said second element being axially displaceable upon application of a predetermined torque, a switch having a displaceable contact connected to said motor for actuating said motor, said contact being disposed in alignment with said second rotatable element in a position to be displaced by displacement of said second rotatable element to deactivate said motor.

2. A rotary impact hand tool comprising a rotatable shaft, an electric motor connected to said shaft to rotate said shaft, a tool spindle, a first clutch element connected to said tool spindle and rotatable therewith, a second clutch element connected to said shaft, said first and second clutch elements having engaged faces with at least a portion disposed obliquely to the axis of rotation, means to bias said second clutch element into engagement with said first clutch element to drive said tool spindle, a switch connected to said electric motor for turning said electric motor on and off and having a displaceable actuating contact disposed in the path of said second clutch element and displaceable thereby to deactivate said electric motor when said clutch elements are displaced relatively by the transmission of a torque greater than said biasing means.

3. A rotary impact hand tool according to claim 1, wherein said first and second elements have a plurality of engageable jaw groups, each of said groups including a jaw element having substantially straight side faces and a jaw element having at least one inclined side face.

4. A rotary impact hand tool according to claim 1, wherein said first rotatable element is connected to said tool spindle, and means to bias said first and second elements into engagement, said second element being movable relatively against said biasing force upon the application of a force suflicient to overcome said biasing force.

5. A rotary impact hand tool according to claim 4, wherein said biasing force acts to bias said second element against relative movement.

6. A rotary impact hand tool according to claim 4, wherein said biasing force acts axially in respect to said elements.

7. An engageable clutch element comprising a member having a circular face with a plurality of jaw groups defined thereon of equal angular extent, said jaw groups including first and second outstanding jaw elements, said first element including a substantially straight face on one side and an inclined face on the opposite side and References Cited by the Examiner UNITED STATES PATENTS 1,145,888 7/1915 FOX 19267 X 2,196,589 4/1940 Jimerson 19230.5 2,543,979 3/1951 Maurer 81-52.3 X

8 Maurer 192-305 X Shaff 192034 Mumford et al 19267 Harrison et al 192-034 X FOREIGN PATENTS Australia. France. Netherlands.

DON A. WAITE, Primary Examiner.

MORRIS M. FRITZ, Examiner. 

2. A ROTARY IMPACT HAND TOOL COMPRISING A ROTATABLE SHAFT, AN ELECTRIC MOTOR CONNECTED TO SAID SHAFT TO ROTATE SAID SHAFT, A TOOL SPINDLE, A FIRST CLUTCH ELEMENT CONNECTED TO SAID TOOL SPINDLE AND ROTATABLE THEREWITH, A SECOND CLUTCH ELEMENT CONNECTED TO SAID SHAFT, SAID FIRST AND SECOND CLUTCH ELEMENTS HAVING ENGAGED FACES WITH AT LEAST A PORTION DISPOSED OBLIQUELY TO THE AXIS OF ROTATION, MEANS TO BIAS SAID SECOND CLUTCH ELEMENT INTO ENGAGEMET WITH SAID FIRST CLUTCH ELEMENT TO DRIVE SAID TOOL SPINDLE, A SWITCH CONNECTED TO SAID ELECTRIC MOTOR FOR TURNING SAID ELECTRIC MOTOR ON AND OFF AND HAVING A DISPLACEABLE ACTUATING CONTACT DISPOSED IN THE PATH OF SAID SECOND CLUTCH ELEMENT AND DISPLACEABLE THEREBY TO DEACTIVATE RELATIVELY BY THE WHEN SAID CLUTCH ELEMENTS ARE DISPLACED RELATIVELY BY THE TRANSMISSION OF A TORQUE GREATER THAN SAID BIASING MEANS. 